Copper is the catalyst for POM degradation, so contact between copper or copper materials and POM melt should be avoided.
1, plastic treatment
The water absorption of POM is low, generally 0.2%-0.5%. In general, POM can be processed without drying, but wet raw materials must be dried. The drying temperature is above 80℃ and the drying time is above 2 hours, according to the supplier's information.
The proportion of recycled materials generally does not exceed 20-30%. However, depending on the type and end use of the product, it can sometimes reach 100%.
2, the choice of molding machine
POM has no stagnation area except screw, and has no special requirements for injection molding machine. Generally, injection molding is enough.
3, mold and gate design
The common mold temperature is controlled at 80-90℃, the runner diameter is 3-6mm, the gate length is 0.5mm, and the gate size depends on the thickness of the rubber wall. The diameter of the circular gate should be at least 0.5-0.6 times of the product thickness, the width of the rectangular gate is usually more than 2 times, the depth is 0.6 times of the wall thickness, and the demoulding slope is between 40'-130'.
exhaust system
The thickness of POM-H is 0.01-0.02mm, and the width is 3mm.
POM-K is 0.04mm thick and 3mm wide.
4、
melting temperature
Can be measured by aerial photography
POM-H can be set to 2 15℃ (190℃-230℃).
POM-K can be set to 205℃ (190℃-2 10℃).
5. Injection speed
It is common that the medium speed is too fast, too slow is easy to produce ripples, and too fast is easy to produce overheating.
6. Back pressure
The lower the better, generally not more than 200bar.
7. Retention time
If the equipment has no glue retention point.
POM-H can stay at 2 15℃ for 35 minutes.
POM-K can stay at 205℃ for 20 minutes without serious decomposition.
At the injection temperature, the residence time of the melt in the barrel should not exceed 20 minutes. POM-K can stay at 240℃ for 7 minutes. If the machine stops, the barrel temperature can be reduced to 65438 050℃. If the machine is shut down for a long time, it is necessary to clean the spool and turn off the heater.